Products of the general character of the aforementioned CORIAN.TM. and FOUNTAINHEAD.RTM. products have been long known and are commonly available such as for use as kitchen and bathroom surfaces. Broadly speaking, these materials are formed of particle filled resins, the most common resins being polyesters and acrylates, and the fillers ranging widely, often used to give particular visual effects to the product. Many prior patents directed to these types of products exist, bearing titles such as "Resinous Product Simulating Onyx" in Schaefer U.S. Pat. No. 3,396,067; "Filled Polymethylmethacrylate Article and Process for its Manufacture" in Duggins et al U.S. Pat. No. 3,827,933; "Process for the Production of Marbleized Reinforced Polyacrylic Compositions" in Miller U.S. Pat. No. 3,663,493; "Thick, Cured Polymethylmethacrylate Article and Process for its Preparation" in Slocum Re. 27,093; "Reinforced Resin Compositions" in Rees et al U.S. Pat. No. 3,789,051; "Use of Alumina Trihydrate in a Polymethylmethacrylate Article" in Duggins U.S. Pat. No. 3,847,865, these being just a few examples of the many, many U.S. patents which exist in this field.
The aforementioned products have achieved remarkable commercial success, especially for tabletops and kitchen and bathroom surfaces, and are normally available in a great variety of appearances. For example, the aforementioned FOUNTAINHEAD.RTM. product is a solid, non-porous surfacing material available in a variety of colors and patterns which run throughout its thickness, giving it a soft, deep translucent and natural feeling of warmth. Yet this material is tough and resists heat, stains, mildew and impact, and can be easily repaired if damaged. The FOUNTAINHEAD.RTM. product line includes soft, neutral solid colors and "granite-like" patterns, as well as grays, black and whites.
Commonly used pigments in these products are composed of small particles of inorganic compounds, often metallic oxides, which are roughly spherical in shape. Other pigments are also sometimes used, as well as fillers and larger pieces of colored material to provide different visual effects. Alumina trihydrate (ATH) is often included as a filler for its particular fire-retardant properties.
Pearlescent buttons have been made for many years by injection molding or the like, using pearlescent and iridescent pigments, and such pigments have been used in other fields as well, such as in the manufacture of bowling balls.
Commercially available pigments of this type, called by various names such as opalescent, pearlescent, iridescent, interference and thermochromatic pigments, are used to give the products in which they are used a sheen, reflectivity and three dimensional look, and it would be desirable to be able to provide such an appearance in surfacing materials of the type with which the present invention is concerned, as broadly described above. However, until the present time this has not been successful for a variety of reasons, including the fact that many of such pigments, here referred to simply as "pearlescent", become buried in the body of the product so that their light reflecting properties become lost.
In addition, these commonly available pearlescent pigments are shear sensitive so that their pearlescent effect is killed by the addition of common opacifiers used in these products, such as titanium dioxide and ATH.